In general, raw paper has so far been used as a substrate for photographic printing paper. For the purpose of imparting a water-resisting property to raw paper, both sides thereof are generally covered with polyolefin resins, such as polyethylene. The photographic printing paper support using a polyolefin-covered raw paper as described above is coated with photographic emulsions on one side thereof. This side of the support is called "front side". The other side of the support on which any photographic emulsions are not coated is called "back side".
In case of a roll-form silver halide photographic material, letters and/or marks have often been typewritten on a backing layer provided on the back side thereof in order to clearly indicate the boundary between neighbouring image planes in anticipation of the photographic material's being automatically cut into image planes or in order to write image information on each image plane.
Therein, the typewriting has caused a trouble such that the typed ink was eluted into a processing bath, the color thereof faded to such an extent as not to fully perform its function, or it partly transferred onto the emulsion layer side when the photographic material was wound up into a roll.
Under these circumstances, some proposals have been made with the intention of imparting satisfactory penciling and typewriting qualities to photographic printing paper. For instance, (i) the photographic printing paper support comprising a polyolefin-covered waterproof substrate having on the back side thereof a written letter-retaining layer constituted of a styrene-acrylate copolymer containing binder and an inorganic pigment (e.g., crystalline silica, colloidal silica) dispersed therein and (ii) the silver halide photographic material containing a carboxyl or sulfo group-containing compound in a backing layer thereof mainly for improvement in antistatic property have been proposed [in JP-A-62-6256 (the term "JP-A" as used herein means an "unexamined published Japanese patent application") and JP-B-03-28696 (the term "JP-B" as used herein means an "examined Japanese patent publication), respectively]. However, those materials can be still improved upon typewriting quality.
Meanwhile, photographic printing paper is manufactured by applying various photographic layers to a support generally measuring 1 to 2 meters in width, cut into sheets or rolls with a long length depending on the end-use purpose thereof, and then marketed.
In supplying roll-form printing papers with a long length, cut pieces of printing paper are overlapped with an appropriate width when they have a length less than the desired roll length, and the overlapped part thereof is thermally fused by a splicing method using ultrasonic waves or so on to splice the cut pieces.
In case of broad photographic printing paper, however, the thermal fusion method, whether it uses ultrasonic wave irradiation or heat application, has a drawback such that it cannot ensure a satisfactorily spliced state to the overlapped part thereof because photographic layers including emulsion layers and coatings on the back side are present between two polyolefin resin-covered supports to adhere to each other.
As a result of our intensive studies for solving the above-described problems, it has been found out that not only an improved typewriting quality but also enhanced spliceability upon thermal fusion utilizing ultrasonic waves or so on can be obtained by forming a backing layer on the back side of a waterproof support comprising raw paper covered with polyolefin resins on beth sides thereof and further by using in said backing layer an aqueous dispersion of polyolefin resin having a melting point below 100.degree. C., thus achieving the present invention.